How does my washing technique induce swirl marks when my motion is side to side?

[Jeff_M]

This has probably been covered before, but my search attempts led me nowhere. During a flight last week, as I looked out the window, I noticed the glass was covered with swirl marks and it got me thinking. Swirl marks are everywhere (not just automobile paint). I acknowledge that marring can be caused by incorrect washing methods, but I am skeptical that such symetrical swirls can really be caused by us. I have always washed my car with horizontal movements. Why then, do I get swirl marks and not horrizontal lines?

 

[Bill D]

You saw the marks on your car while viewing them from the window of an airplane?





If the swirls marks look like cobwebbing/spider webs, this is the opitical effect from thousands and thousands of tiny scatches or marring. It still could be that although you wash in one direction, when viewed under the lighting source, it still may look like swirls.



Now, if we're talking, random, here and there curve shaped light scratches, that sounds like something abrasive randomly made contact with the paint. It can be tough to pin point exaclty what. Could be from driving, a rogue particle of dirt in a wash mitt or MF, etc., etc.

 

[Accumulator]

IIRC it has something to do with the way refractions of light tend to "radiate" from where the light source hits the paint, a sort of optical illusion. Sorry I can't explain it better, wish I'd paid closer attention in science class



In some lighting, you will probably see the straight marring as, well, straight lines. A friend of mine always does things front-back, but in the sun and under streetlights, the car looks "swirled", with the marring appearing to be sorta circular/elliptical. In my shop (controlled lighting conditions) the circular swirls will look more/less like straight lines depending on how I play with the lighting and viewing angle.

 

[Jeff_M]

You saw the marks on your car while viewing them from the window of an airplane?

Sorry. That made no sense, so I edited my post accordingly.

 

[Bill D]

OK, I was just wondering. I'll second what Accumulator added.

 

[Jeff_M]

IIRC it has something to do with the way refractions of light tend to "radiate" from where the light source hits the paint, a sort of optical illusion. Sorry I can't explain it better, wish I'd paid closer attention in science class



In some lighting, you will probably see the straight marring as, well, straight lines. A friend of mine always does things front-back, but in the sun and under streetlights, the car looks "swirled", with the marring appearing to be sorta circular/elliptical. In my shop (controlled lighting conditions) the circular swirls will look more/less like straight lines depending on how I play with the lighting and viewing angle.

Very interesting. So the actual marring isn't in a swirl pattern. Makes more sense now.

 

[imported_animes2k]

interesting, though, that an improperly used rotary will show obvious swirls. i don't know what this means, i just find it interesting

 

[Bill D]

When it comes to rotary induced swirls, there's probably even more variables ,quite a list I imagine, that can contribute. He he, that's a big topic for a whole other, long thread.

 

[Lowejackson]

I cannot find the thread where Mike Philips explains these effects with some great pics. In essence it is as Accumulator explained, it is a trick of the light

 

[imported_pdsterns]

Here is the answer



http://www.amasci.com/amateur/hand1.html



http://autopia.org/forums/showthread.php?s=&threadid=45858